This invention relates generally to the manufacture of sealed packages of the type comprising a bag length of tubing of flexible packaging material having heat seals at the ends for sealing product therein, the packages being of the type, e.g. the pillow type with or without gussets, three-side or four-side sealed packages, that may be produced, for example, by a vertical form-fill-seal machine (a "VFFS" machine) such as that disclosed in U.S. Pat. No. 4,288,965 of Robert C. James, issued Sept. 15, 1981 to Hayssen Manufacturing Company of Sheboygan, Wis., denoted the ULTIMA.RTM. machine, ReExamination Certificate B1 4,288,965 issued Mar. 26, 1985, and by a horizontal form-fill-seal machine (an "HFFS" machine) such as that disclosed in U.S. Pat. No. 3,274,746 of Robert C. James et al. issued Sept. 27, 1966 to Hayssen Manufacturing Company, denoted the RT machine.
The invention is more particularly directed to the manufacture of sealed reclosable packages of the type described in pending U.S. patent application Ser. No. 477,291 now abandoned and a pending continuation-in-part thereof, Ser. No. 499,951, both assigned to Hayssen Manufacturing Company. This package has a reclosable (resealable) closure extending lengthwise of the package inwardly of and adjacent one side edge of the package, and a built-in easy open feature involving a cutting string disposed inside the bag adjacent the one side edge of the bag, the string being accessible so that it may be pulled to cut the bag along the one side of the bag to open it without the use of extraneous means such as a scissors or knife.
The flexible packaging material used in the production of reclosable bags of the type described above is manufactured in web form, the web having a pair of spaced-apart parallel reclosable closure strips (e.g., an elongate channel member and a mating tongue member) extending longitudinally of the web on one face of the web inwardly from one side edge of the web, and a cutting string on the one face of the web extending between the closure strips and generally parallel thereto. For ease of handling and shipment, and to prevent damage to the closure strips prior to manufacture of the web into packages, the web is typically wound in roll form with the web, as wound, in a folded condition in which the web is folded along a fold line extending generally midway between and parallel to the closure strips (immediately adjacent the cutting string) so that a portion of the web between the fold line and the one side edge of the web is folded over on the web, with the closure strips interlocked.
In the manufacture of packages from such web material, as by a horizontal form-fill-seal ("HFFS") machine or a vertical form-fill-seal ("VFFS") machine, folded web is fed from a supply roll, opened (unfolded) in such a way that the closure strips remain interlocked, and then fed to the packaging machine. Heretofore, the web-opening step has been accomplished by unfolding the folded-over portion 180.degree. relative to the remainder of the web (with the closure strips remaining interlocked). However, this method causes uneven tensioning of the web across its width as the web is pulled forward, which in turn causes inaccurate tracking of the web as it travels to the bag-forming apparatus, and other problems.